A dynamic and energetic politician, Theodore Roosevelt is credited with creating the modern presidency. As a young Republican, Roosevelt held a number of political posts in New York in the 1880s and '90s and was a leader of reform Republicans in the state. In 1898, as assistant secretary to the U.S. Navy, Roosevelt vehemently advocated war with Spain. When the Spanish-American War began, he formed the "Rough Riders," a volunteer cavalry that became famous for its contribution to the United States victory at the Battle of San Juan Hill in Cuba. The publicity-minded Roosevelt rode his military fame to the New York governor's seat in 1898 and to the vice presidency in 1900.
In 1901, President William McKinley was assassinated, and Roosevelt, 43 years old, became the youngest president ever to assume the office. He stamped the presidency with a vitality that delighted most Americans and was elected to a second term in 1904. As an American expansionist, Roosevelt asserted his executive powers to defend U.S. interests throughout the Americas as he sought to balance the interests of farmers, workers, and the business class at home. He insisted on a strong navy, encouraged the independence of Panama and the construction of the Panama Canal, promoted the regulation of trusts and monopolies, and set aside land for America's first national parks and monuments. In 1906, he was awarded the Nobel Peace Prize for his mediation in the negotiations to end the Russo-Japanese War.
In 1912, three years after finishing his second term, Roosevelt ran for president again as the new Progressive Party candidate. Challenging his former vice president, President William Howard Taft, he campaigned on his "Square Deal" platform of social reform. In November, the divided Republican Party was defeated by Democrat Woodrow Wilson.
In the last few years of his life, Roosevelt became a vocal advocate of the U.S. entrance into World War I and even sought to win a commission to lead a U.S. Army division in Europe. President Wilson declined, and after the war Roosevelt was a vocal opponent of his League of Nations. In 1919, Roosevelt died at his home in New York. The tropical diseases he had contracted during his travels likely caught up with him, and he died at the age of 60.